Dell USB-C monitor with 2017 MacBook

Hi folks - a good old-fashioned support question. I got a new Dell USB-C monitor (a U2719DC), but it doesn’t work with my 2017 Macbook over USB-C. All standards seems to indicate it should - the cable is USB 3.1, the monitor allegedly supports DisplayPort 1.4 over USB-C, MacBook allegedly outputs DisplayPort 1.2 over USB-C, but no dice. When I plug it in, the monitor claims "no USB-C input from your device", although the MacBook does take a charge over the cable.

I've googled and there doesn't seem to be any firm conclusion on whether it should work at all, let alone how to fix it. Lots of people using MacBook Pros or Airs, not many using the "vanilla" MacBook. It's possible it just won't work because standards aren't. Neither Dell nor Apple nor the place I bought the cable from explicitly say they should all work together over USB-C. I could return it in the next few days, although it does work just fine over HDMI using the Apple HDMI adapter, and I'm overall happy with the thing, so I'll probably hold on to it either way.

But assuming that standards are standards, I feel like I should be able to get it to work. Any ideas?

Edit: I've just ordered the Belkin cable from the Apple store, which at least says specifically "Transfer data from a MacBook or MacBook Pro to another USB-C–enabled host or device, or connect to a DisplayPort-enabled USB-C display for video resolutions of up to 4K." So we'll see how that goes, was hoping to avoid a $40 cable on top of everything else but their return policy is pretty generous so it's worth a crack.

Well, dell f’d up and didn’t include it, so I’m waiting on them to ship me the one it’s supposed to come with. Instead I’ve tried both the Apple C-C cables I have. I can’t tell them apart, I’m fairly sure that one is a ‘charge cable’ ie no capacity, but I think that the other is a TB3 cable, which I think should also do DisplayPort over USB-C, but maybe it doesn’t, who knows. If only there was some way to visibly tell what a given USB-C cable is supposed to do…

dal20402, I hope you’re right. I mean, you’re definitely right about the hell part.

AFAIK, it shouldn't be this difficult. Yes, there are some variations in USB-C cables, but it's not like you have to specifically support each possible protocol. The main things are:

- 3 vs 5 amps: in order to charge with more than 60 W you need a 5 amp cable, such as Apple's charging cable

- fully wired or USB 2.0 only. As far as I know, fully wired cables support all protocols that USB-C can carry, like Thunderbolt 3. But in order to keep charge cables from getting too thick and unmanageable, they often only have the USB 2.0 wires (such as Apple's).

- short or longer. Fully wired USB-C cables that are no longer than 50 cm can support Thunderbolt 3 at 40 Gbps. Longer ones only support 20 Gbps. I don't think this matters for other protocols, which top out well below 40 Gbps anyway

If the two cables are physically identical, they are both charge-only cables, based on what I see on their website. Their TB3 cable has a lightning bolt on the plastic housing near the connector. The charge only cable is just white.

Quote:

AFAIK, it shouldn't be this difficult.

It shouldn't be. Apple should have sacrificed $0.50 of the $17 of margin they are collecting from these cables to make them all full featured.

It shouldn't be. Apple should have sacrificed $0.50 of the $17 of margin they are collecting from these cables to make them all full featured.[/quote]

I have two additional charging cables in addition to Apple's, and those three are all 4 mm or a hair thinner. The USB-C cable that supports 20 Gbps Thunderbolt is almost 5 mm in diameter. Sounds like a small difference but it certainly makes everything more difficult, so I understand why Apple would use a thinner USB 2.0 "charge" cable. Especially as you really need it to charge your computer so there's not much point in it supporting other functions.

Then again, even if you understand all of this buying the right cables is a huge challenge due to lack of consistent naming/labeling.